In a trench metal oxide semiconductor (MOS) barrier Schottky (TMBS) device, polysilicon is contained inside a trench that is formed in a silicon substrate. The polysilicon inside the trench and the silicon mesa (the surface between adjacent trenches) are connected locally using a metal contact.
In a monolithically integrated TMBS and MOS field effect transistor (MOSFET) device, which may be referred to herein as a SKYFET device, polysilicon is contained inside a trench that is formed in a silicon substrate. The source of the MOSFET section and the TMBS section are connected by the same contact metal.
In both of these types of devices, the polysilicon is separated from the sidewalls of the trench by an oxide layer. During fabrication, a portion of the oxide layer and a portion of the polysilicon are etched away prior to deposition of the contact metal. Unfortunately, the etch process can result in the encroachment of the metal into the sidewalls of the trench (into the mesa), resulting in excessive current leakage often attributed as edge leakage in Schottky diode technology.